Health experts hope data out of Texas will raise awareness about a type of infection commonly spread through kissing bugs.
Researchers with Texas A&M University and the Texas Department of State Health Services analyzed state health data and found it supports classifying Chagas Disease as endemic in the U.S., meaning consistently present in a community like the common cold and strains of influenza.
The U.S. doesn't have standardized surveillance of Chagas, and that can make its presence difficult to study.
But Texas is one of just eight states that document cases and can play an important role in proving its endemic status, according to Sarah Hamer, an epidemiologist with Texas A&M's College of Veterinary Medicine & Biomedical Sciences. That's because Texas data includes information on whether the transmission occurred locally.
"We were able to show this kind of constant expected presence of these locally acquired cases," Hamer said. "Albeit at a low level, but it's here."
Chagas is considered endemic in 21 countries in North and South America, but not in the U.S. Triatomine insects, also called kissing bugs or cone-nosed bugs, can be found in 32 states in the southern half of the country, Hamer said.
For human Chagas disease, transmission typically occurs when someone is bitten by a kissing bug and the feces of the bug get into the blood stream. Animals, like dogs, will also get the virus when they eat an infected bug. Hamer said.
Chagas has been a "notifiable disease" in Texas since 2013, meaning the state documents cases and collects data to inform public health decisions.
Texas has the highest number of locally acquired human cases of Chagas disease, Hamer said. Between 2013 and 2023, the Texas Department of State Health Services documented 50 probable and confirmed cases in which transmission occurred without travel or migration.
"This is just the tip of the iceberg because not every case of human Chagas disease that is transmitted in the United States will be detected or diagnosed," Hamer said.
Endemic status could increase awareness
No one knows exactly how many people in the U.S. have Chagas disease, but scientists estimate at least 300,000 people have Chagas.
Researchers said their main goal is to raise awareness of Chagas disease. Doctors and veterinarians need to be more aware of Chagas to ensure people and animals get properly diagnosed, said Bonny Mayes, a state health department epidemiologist.
"There's a misconception that it is not here and that it is only something that we see, you know, as far as travel-associated cases, or we see it in immigrants," Mayes said. "But that's not really the case with Chagas disease. It's been here for a very long time."
The risk of Chagas is low in the U.S., especially when compared to other countries. That's in part because the disease has an "ineffective" form of transmission, Mayes said — not every kissing bug has the parasite, and feces don't make it into the wound every time there's a bite.
The risk of transmission can be attributed to how often someone is exposed to kissing bugs. That means people who often work outside or live in homes bugs can easily access are more likely to encounter Chagas.
Chagas is divided into two phases: acute and chronic. It can be cured with medications that are 100% effective if administered close to when the infection occurs. Without treatment, patients develop chronic Chagas disease, which can present with or without symptoms.
About 70-80 percent of people remain asymptomatic forever, Mayes said, but the rest can experience heart issues including heart failure, and sometimes digestive system issues.
Heart issues can also occur in pets or animals infected with Chagas.
"You don't know, if you're infected, if you're going to be one of those unlucky ones that goes on to develop actual symptoms later in life," Mayes said.
What can people do?
Chagas can be complicated for a few reasons. Symptoms can be mild and vary. If symptoms occur in the acute phase, they'll usually happen within two weeks and can include fever, rash and swelling.
The most specific indicators of Chagas are redness and swelling around the bite site — different from an allergic reaction which commonly occur with these types of bites — and what's known as Romaña's sign. This occurs when the parasite gets into the eyelid and causes it to swell up, usually when someone accidentally rubs their eye or a bug bites near the eye.
It's difficult for doctors and vets to treat and diagnose patients if they aren't aware of the disease.
"I can tell you that I have emailed with and spoken to many very frustrated people that have been in contact with these bugs," Mayes said. "Because they go to a provider and they're told things like, 'we don't have this disease," or, 'I can't test for that,' or they don't know how to test for it."
Testing can also be complicated, especially for the chronic phase, but the state has resources online for health care providers, Mayes said. The state also provides public health consultation for Chagas.
Because of the mild, nonspecific nature of most of the symptoms, diagnosis and treatment can depend on a person knowing if they've been bitten by a kissing bug. However, there are several species of bugs that look similar, like assassin bugs or leaf-footed bugs.
There are resources for people to learn more about what kissing bugs look like at different stages of life, including Texas A&M's community science program site. The Texas Department of State Health Services also tests bugs that are "implicated in human exposure." It requests people send a photo of the bug to identify if the bug is a kissing bug before shipping the sample.
The Citizen Science Group at Texas A&M collects samples sent in from people who have found kissing bugs in places like their home, yard or parks. The university also has an interactive map that shows from where kissing bug samples originated. However, the university highlights that a lack of submission on the map from a given area, "does not imply that kissing bugs do not occur there."
The map shows the lab received samples from almost every county in north Texas.
Experts recommend limiting and supervising time spent outside for children and pets, ensuring windows and doors are properly sealed, and covering skin to prevent bug bites.
Researchers also said they're hopeful this data may lead to more data and research into kissing bugs and the presence of Chagas disease in the US. Hamer, with Texas A&M, said the researchers recognize how costly disease reporting can be to public health departments, but still hope classifying the disease increases data collection.
"What we learn here will certainly be relevant to fighting the disease across Latin America as well, and vice versa," Hamer said. "I'm hoping that this declaration of endemicity is going to open up conversations to talk about, does it make sense for the disease to be reportable in some states where it currently isn't?"
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